Inspection rounds are frequently performed at many plants. An inspection round involves that a person, such as a member of the plant operation team, moves through certain sections of a plant in order to inspect the status or condition of equipment, as well as status of production. Examples of such plants are process industries, ships and commercial buildings. At these types of plants, and similar plants, there are large numbers of equipment of different types with at least one rotating member. This type of equipment, such as a rotating machine, is typically monitored at inspection rounds, by means of embedded electronics, by means of control systems or in different combinations of these approaches for monitoring. In process industries it is common that equipment that are critical for manufacturing and/or for running a process are monitored on-line, for instance by local control means or by a distributed control system. Other types of machines, with at least one rotating member, that are considered non-critical are often not monitored on-line due to cost reasons. Examples of such machines are fans, certain pumps and conveyors for waste. Such non-critical equipment may be remotely located at a plant. Measurements based on autonomous measurement methods are rarely applied on such equipment or machines. A reason is that available methods are based on measurement devices and systems that are fairly expensive, difficult to install, costly to maintain or that measurement data are difficult to interpret. A much more common approach is that a deviation from a normal state of operation of such a rotating machine is individually evaluated by a person at an inspection round. Such an evaluation is often based on that the person listens in order to detect sounds and noise and/or touch the equipment to sense if a member of the equipment is un-balanced. A person performing an inspection round may also touch the equipment in order to get an indication on an increasing temperature, which may be due to a defect, for instance in a bearing.
Another problem at inspection rounds is to be able to track if a certain piece of equipment, such as a rotating machine, has been passed at an inspection round within a certain time interval measured from a previous made inspection round. The state of the art shows a number of systems that tracks stations, with time stamps, that persons have passed during inspection rounds. For instance persons of a security company monitoring a building, but the state of the art does not present how to achieve efficient tracking of condition monitoring of equipment, such as rotating machines.
Yet another problem is to, in an efficient manner, enable the identification of equipment with at least one rotating member. In a control system or a maintenance system a certain nomenclature is used to identify different types of objects, for instance rotating machines. A fan may for instance have a tag such as FAN14637. But the tag name used in the control system or the maintenance system is rarely used in order to physically mark the fan, such as with a small sign. Even more unusual is to mark the fan with an electronic identification. And it is unusual that fans, and other rotating machines, that are un-connected to means for computerized communication, hence lacking communication capabilities to a control system, is able to send a unique identifier to a receiving unit. Methods to identify such equipment are commonly based on identification in a computerized plant system, in a maintenance system or in an industrial control system. That a person is unable to identify equipment with at least one rotating member, during an inspection round, is a frequently occurring problem. At many plants a substantial amount of man-hours is spent on that a person standing next to a piece of equipment needs to identify the equipment, for instance in collaboration with a plant operator or another person handling a maintenance system. It is unusual that equipment with a rotating member has a means that enable its identity to be electronically communicated, locally, at the equipment. Even if the equipment is connected to computerized communication network, such as a field bus, and has a unique identifier known within the fieldbus environment, a person being in the vicinity of the equipment is unable to identify the equipment without access to a control system, a maintenance system or similar systems.
RFID devices are available as commercial products. Other commonly used names on an RFID device is an RFID tag or an RFID transponder. An RFID device stores a unique identity that is read by wireless receiver. The receiver may be handheld or mounted at a construction member, for instance at a conveyor belt. An RFID device communicates with a wireless receiver by means of a magnetic field. Other terms that are frequently used in this context are an electric field, radio waves or electromagnetic field. Examples of field of use for RFID are as tags for products, such as tags on containers or boxes, goods, vehicles or steal products. Another example of field of use is as tags on components intended for assembly to a product within a plant.
RFID devices may be active and contain an own source of energy, such as a battery. With RFID units used as tags, for instance for containers, boxes and goods, it may not be an issue that a battery has limited life span. Such a RFID tag is used during the distribution and the logistic handling, hence has no critical function in later stages. An RFID tag that has no planned end-date for use, such an RFID device mounted at a certain position in a plant, the need to change the battery becomes an issue. One draw back is that one may miss out important readings when a battery becomes empty. Another drawback is that RFID devices used in harsh environments may need to be encapsulated in order to withstand dust and moisture, which in turn makes the design of such device advanced and costly in order to be able to change the battery.
RFID devices may also be passive and activated by means of an inductive circuit. Such an RFID device may for instance be activated as it passes an RFID receiver mounted at a conveyor belt. A problem with such a passive RFID device, with an inductive circuit that is energized by means of a magnetic field, is that compared to an active RFID device it is necessary to transfer more energy from the RFID receiver in order for the RFID device to communicate with the receiver. The receiver must energize the device. When a fixed RFID receiver is used the problem might be less severe since the receiver may be continuously supplied with electric energy by wire. But when a handheld RFID receiver is used, the minimization of the transferred amount of energy from the receiver is an issue. A handheld receiver is typically equipped with a re-chargeable battery. The more energy that is needed to activate the RFID devices, the less number of readings is possible before the battery of the handheld receiver needs to be recharged.
Another problem with use of RFID in plants with rotating machines is that the electronics must be protected from the harsh surroundings. This leads to that such an RFID device should be enclosed, preferably airtight and without openings such as covered with a lid. For such an RFID device a regular battery is not an option. Plants with such environments where RFID devices needs to be enclosed, preferably airtight and without openings such as covered with a lid are, for instance, process industries for manufacturing or processing of steel, other metals, pulp, paper, chemical or petrochemical industry. Other examples of plants are sites for production, transport refining of oil, gas or minerals. Other examples of plants are means of transport such as a train or a ship. Other harsh environments where inspection rounds are common are ventilation systems, in particular those with a number of fans, in commercial buildings or apartment buildings.
US 2004/0004131 shows an RFID tag capable of surviving high temperatures. The RFID is enclosed and is made as a laminate of heat resistant material and comprising a window for an RFID generating component. One out of several drawbacks with the tag is that it does not perform any physical measurement.
An RFID device with temperature measurement capability is described in US2004/0041714. A wireless communication unit is described, receiving indications of temperature relating to a container and/or its contents and communicating such a temperature indication together with an identifier to a receiver. The wire less communication unit measures and communicates temperature indications relating to the container in a repeated manner. One out of many remaining problems with the wire less communication unit is that it is not intended or suitable to be mounted on a rotating machine or monitoring a rotating machine. Yet another draw back is that the unit does not perform any vibration measurements.
There are a number of commercial systems for condition monitoring of equipment with at least one rotating member, such as a rotating machine. Such systems are for example a system for vibration measurement or vibration analysis. The systems handle measurements, for instance by means of Fourier analysis or neural networks. Some systems comprise a handheld device, such as a microphone, which a user handles in order to initiate a measurement of a machine. There are known systems which comprise devices/transmitters mounted on a machine. These devices/transmitters are energized by means of electricity through a cable or wire. There are also devices/transmitters with a battery. With previous known devices and systems it is not suitable to use devices that are energized with RFID or technology similar to RFID, as a great amount of energy is used at measurement and transfer of the great amount of data, which is necessary for vibration analysis. Such systems do not have vibration transmitters or devices mounted on machines which are independent of a battery or electric connection. There are systems for condition monitoring that use wireless communication with such a transmitter for instance based on Bluetooth. But a Bluetooth device that is connected to such a transmitter/device is dependent on a battery or an electrical power connection in order to send data from the transmitter.